It depends on what you want to do or prefer. For my son's 1946 3/4 ton, the first two leaves (based on the Chevrolet specs doc) are the same between a 1/2 ton and 3/4. I found a pair of 1/2 ton springs for very little money and just changed the first two out. We aren't necessarily trying to keep it to that level of original, it was just a cheap alternative.
I'm sure a spring shop can build you a completely new set that would give you a lot of service and might be the better alternative if you plan to drive it a lot.

1946 3/4 ton